Last year, a panel of the Fourth Circuit decided United States v. Graham, 796 F.3d 332 (4th Cir. 2015). The panel ruled that “the government conducts a search under the Fourth Amendment when it obtains and inspects a cell phone user’s historical [cell site location information (CSLI)] for an extended period of time. . . . Its inspection by the government, therefore, requires a warrant, unless an established exception to the warrant requirement applies.” I discussed Graham here and here. Last week, the en banc Fourth Circuit reversed the panel, ruling that under the third-party doctrine, a cell phone subscriber has no reasonable expectation of privacy in historical cell site location information that he or she shares with a service provider, so it isn’t a Fourth Amendment “search” when law enforcement obtains such information, and a warrant isn’t required. The en banc opinion is here. This post discusses the opinion and considers the possibility of Supreme Court review or action by Congress.